I am working with the STM32L552 microcontroller in a critical application where a portion of the external circuit relies heavily on the 2.5 V VREF+. The stability of this reference voltage is essential, that is if the VREF+ should go above 2.5 V, it would scale other circuits which could lead to undesired behavior.
Is there a way to monitor the VREF+ buffer output using the VREFINT internally within the STM32L552? I specifically want to detect any event where the VREF+ goes above its nominal value. Now the tricky part is that I do not have any pins available where I could have used the internal comparators. Of course I could attach an external reference to decouple the circuit from the MCU, but I want to investigate whether there is anything I could do internally.
(Edit) A portion of the application circuit is below. Essentially, the Vref+ output buffer from the STM32 is used in a high side current sense comparator circuit. The STM32 DAC which is referenced to VREF+ is used to regulate a low sense current sense drive. If the VREF+ goes above 2.5 V, then it scales the high side sense as the low side driver drives for current through. I want to know whether it is remotely possible to detect this internally within the STM32L552.
simulate this circuit – Schematic created using CircuitLab
Any suggestions regarding hardware configurations, ADC settings, or software approaches are highly appreciated.
